1. Field of the Invention
The present invention is generally directed to a set top board for activating video on demand (VOD) service. More particularly, this invention relates to a set top board which can be mounted in a slot of a personal computer and can provide the VOD service program on a monitor or the personal computer as visible and audible signals for the computer user, and to a computer system comprising such a set top board.
2. Description of Related Art
Video on demand (hereinafter, referred to as "VOD") service means a service system in which subscribers or customers can interactively choose various programs stored in a video source and can watch a program they desire at any time, rather than just receiving preset TV programs from broadcasting stations. The VOD subscriber can manipulate the selected program, as the user of VCR, including replay, rewinding, pause, and recording of the served video program. Moreover, various video and audio services such as video games, home shopping and video conferencing can be offered to the users in the VOD service system. In view of this expansion of the serviced extent, VOD service is also called an interactive TV service, or called video dial tone service in that telephone companies may participate in the video market.
In order to realize the VOD service, a user's terminal, such as TV receiver, needs to have an interfacing means for transferring the selected video program signal to the server and for decoding or recovering compressed video data transmitted from the server in response to the selected program signal. Recently, so called "set top boxes" have generally been used as the interfacing means in an interactive TV receiver.
An earlier VOD service system, which was normally placed on top of the television receiver, interfaces a television set with a server which can compress, store, and manage a large amount of data for servicing desired TV programs to customers. A T1 network communicates interactively but asymmetrically the video data between the server and a set top box (STB). The T1 network can downstream transfer image data at a high speed while upstream transfers data at a low speed. The STB receives and processes VOD service data from the server via the T1 network and transfers image data to the TV receiver. The TV receiver is provided with a display for showing to subscribers VOD service items and image data corresponding to the selected service item transmitted via the STB. The STB may be operated via a remote controller utilizing the display of the TV receiver.
The STB normally includes a power supply, a remote controller signal receiver for receiving and decoding the command signals from the remote controller, a T1 networking part for communicating with the server of the VOD service system via the T1 network, video processor for processing the list of the service items transferred in the form of image data into still images, an MPEG (motion picture experts group) decoder for recovering original video data from compressed MPEG data which is transmitted from the server and corresponds to a particular service item selected by the user, a video encoder for receiving the recovered data from the MPEG decoder and for transferring the received data to the TV as picture data and an audio processor for processing audio data contained in the VOD service program. A central processing unit CPU of the STB controls the above components.
The server stores data, such as movies, games and educational programs, necessary to service data corresponding to the service item for the subscribers and interactively transfers data when connected to the STB via the T1 network.
The server transmits a list showing the service program items to the STB in the form of image data and the STB passes the list from the server to the TV receiver in a still image format.
The user chooses an item to be serviced from the list displayed on the screen of the TV receiver and then transfers information as to the selected item back to the server. The server transfers compressed MPEG image data corresponding to the selected item to the STB via the T1 network. The STB recovers the received MPEG data and transfers the recovered image data to the TV receiver which displays the selected VOD service.
Such an STB has the following disadvantages.
Firstly, the STB must be connected to a TV receiver in order to receive image data serviced from the VOD service system.
Secondly, due to the first defect of the STB, when a user want to save, edit, or fast forward or rewind a certain motion picture, a multi-media personal computer, having an overlay board which can receive and process image data of the motion picture, is needed. In this case, digital image data received by the TV receiver must be transformed to analog data and the analog data must again converted into digital data to be saved or edited as the user wants. As a result, data may be lost in the data conversion steps.
The Schupak patent, U.S. Pat. No. 5,557,675, entitled Computer Controller Audio-Visual System, discloses an arrangement in which a computer directly interfaces an audio/video signal with one or more television receivers. However, there is no indication that the system is operative with an interactive video on demand service as in the present invention.
The Hodge et al. patent, U.S. Pat. No. 5,594,491, entitled Near-Video-On Demand Digital Video Distribution system Utilizing Asymmetric Digital Subscriber Lines, discloses a video on demand distribution system utilizing a set top box but does not teach or suggest the use of a set top box contained in a card within a personal computer as in the present invention.
The Remillard, U.S. Pat. No. 5,461,667, entitled Apparatus And Method For Electronic Device For Information Services, discloses an arrangement in which an electronic device 20, which appears to be a special purpose computer, is disposed between a television 50 and a communication medium 32. While the Remillard '667 system has interactive capability, Remillard '667 does not teach or suggest a set top board for a video on demand service contained within a card within a personal computer as in the present invention.
The following patents each disclose features in common with the present invention but do not teach or suggest a set top board for a video on demand system contained within a card mounted within a personal computer as in the present invention.
U.S. Pat. No. 5,512,935 to Majeti et al., entitled Apparatus And Method For Displaying An alert To An Individual Personal Computer User Via The User's Television Connected To A Cable Television System, U.S. Pat. No. 5,442,390 to Hooper et al., entitled Video On Demand With Memory Accessing And Or Like Functions, U.S. Pat. No. 5,416,508 to Sakuma et al., entitled CATV system With Transmission Of Program Schedules, Linked Program Broadcasts, And Permissive Ordering Periods, U.S. Pat. No. 5,359,367 to Stockill, entitled Personal Computer With Broadcast Receiver On Expansion Board Controlled By Computer Microprocessor, U.S. Pat. No. 5,541,662 to Adams et al., entitled Content Programmer Control Of Video And Data Display Using Associated Data, U.S. Pat. No. 5,523,781 to Brusaw, entitled System For Controlling Television And Billing for Its Use, U.S. Pat. No. 5,621,482 to Gardner et al., entitled Interface System For A Television Receiver, U.S. Pat. No. 5,592,234 to Gardner et al., entitled Interface System For A Television Receiver, U.S. Pat. No. 5,594,492 to O'Callaghan et al., entitled Method And Apparatus For Rapid Channel Selection, and U.S. Pat. No. 5,594,507 to Hoarty, entitled Compressed Digital Overlay Controller And Method For MPEG Type Video Signal.